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Abstract. To avoid the leaf burns caused by fertilizes intercepted in crop canopy during sprinkler fertigation, fertilizer concentration for a center pivot fertigation system should be carefully selected. Field experiment was conducted to study the effect of fertilizer solution concentration fertigated from a center pivot on plant height, leaf area index (LAI), SPAD, chlorophyll fluorescence characteristics, and yield of summer maize in the North China Plain. Five solution concentrations in mass fraction of 0.048%, 0.105%, 0.146%, 0.178%, and 0.312% (referred to as N1, N2, N3, N4, and N5) were tested. Urea and ammonium sulfate mixed in a mass ratio of 3:1 was applied during jointing stage of summer maize. The total amount of nitrogen applied in the whole growth season, including the basal fertilizer of 132 kg ha^-1, was 170, 215, 248, 273, and 380 kg ha^-1 for N1, N2, N3, N4, and N5, respectively. The results indicated that there was no significant difference in plant height, LAI, and SPAD for the five nitrogen rates tested. When a concentration of solution lower than or equal to 0.105% was used, a fertigation event would significantly increase the PSII activity Fv/F0 and the photochemical efficiency Fv/Fm of plant compared to the values prior to fertigation. However, a significant reduction of Fv/F0 and Fv/Fm was observed when the fertigation concentration used was greater than 0.105%. The yield of N2 treatment (12.5 t ha^-1) was significantly higher than that in N3, N4, and N5 treatments, while there was no significant difference in yield between N1 and the other treatments. The results suggested that fertigation through center pivot could improve the photosynthetic activity of plant and enhance the efficiency of fertilizer production when a favorable fertilizer solution concentration was selected. A nitrogen rate of 215 kg ha^-1 that was fertigated at a concentration of 0.105% was recommended for sprinkler fertigation by this study.